In 1992, the United States Environmental Protection Agency adopted a standard for lead and copper in municipal drinking water. The standard sets action levels for lead and copper in standing samples collected from faucets with the highest risk for elevated lead and copper levels. The action level for lead is 15 .mu.g/liter of water; the action level for copper is 1.3 mg/liter of water. The source of these and other metals in drinking water is primarily corrosion of plumbing system components, which include copper and lead-based solder as well as carbon steel and brass. Current anticorrosion additives, which include phosphate salts and/or zinc salts, have been in use for many years, but do not always provide adequate protection. There remains a need for improved corrosion inhibitors which are not themselves likely to present a health hazard when added to water.
Co-owned U.S. Pat. Nos. 5,202,058 and 5,510,057 describe the use of stannous salts, such as stannous octanoate or stannous chloride, typically in combination with other additives, in an alcoholic solvent medium, for reducing metal corrosion in, for example, cooling water tower systems. However, these additional components, including the alcoholic solvent, would be undesirable or even prohibited for use in drinking water supplies. Alcoholic solvents can provide a food source for the growth of bacteria and thus impact the sterility of drinking water supplies. Reduction in microbial growth would be beneficial in industrial water supplies as well. Accordingly, there is a need for effective corrosion inhibitors which minimize organic content.